The present invention relates to the art of blasting with explosives and to the use of non-electric delay detonators. More particularly, the invention relates to a non-electric detonator assembly which may simply and conveniently be attached to an initiating length of low energy detonating cord in the field.
To avoid the hazards associated with the use of electrical initiation systems for detonating explosive charges, wide use is now made of non-electric blasting caps, both delay and non-delay, which caps are initiated by means of a connected length of low energy detonating cord (LEDC). To initiate a charge of explosives placed in, for example, a borehole, a detonator (blasting cap) is fitted with a length of LEDC by crimping one end of the LEDC into the detonator. The detonator is placed in contact with the blasting charge (or an appropriate booster) in the borehole and the remote end of the LEDC is initiated. The shock transmitted along the LEDC sets off the attached detonator which, in turn, initiates the blasting charge or booster. Networks of such charges can be provided to produce time-delay blasting and are shown for example, in U.S. Pat. No. 3,878,785. An essential component of these disclosed methods is the factory-assembled, non-electric detonator (whether instantaneous or delay) having an integral length or "tail" of LEDC inserted therein. These LEDC tails are, by the use of appropriate connecting devices as shown in U.S. Pat. No. 3,878,785 or U.S. Pat. No. 3,175,491, brought into contact with an initiator, generally a trunk line of detonating cord.
There has been a need in the blasting art for an LEDC-initiated detonator which may be attached to the LEDC in the field. Such a detonator would reduce the requirement to supply factory-assembled units having various LEDC tail lengths and, consequently, would reduce inventories and manufacturing problems. In the field, the blasting technician could adjust the length or tail of LEDC as required as he prepared his blasting network and hence reduce waste.